Heterotopic ossification (HO) is the pathologic formation of extra-skeletal bone in soft tissues. Vanden Bossche and Vanderstraeten, J Rehabil Med 27, 129 (2005). This process occurs in patient populations with severe trauma including large-surface area burns, musculoskeletal injury, orthopedic operations, and spinal cord injury, and in patient populations with a genetic disease known as fibrodysplasia ossificans progressiva (FOP). FOP is caused by a hyper-activating mutation in the type I bone morphogenetic protein (BMP) receptor ACVR1, and patients with FOP develop ectopic bone lesions in the absence of any substantial trauma. The clinical sequela of these pathologic ectopic bone formations, whether in the setting of trauma or genetic mutations, include non-healing wounds, chronic pain, and joint immobility. In the case of FOP, progressive ossification may lead to death due to loss of thoracic cage compliance.
Treatment options for HO are limited as bone often recurs following surgical resection, and some patients may have non-resectable HO due to its sensitive location. The risk of an operation may outweigh the benefits of excision, especially in the face of recurrence. There is a need for therapeutic options which can prevent HO before its initial occurrence in at-risk patients.